The process for such an apicoectomy is described in detail by Kirschnet, "Atlas der chirurgischen Zahnerhaltung", Munich/Vienna 1987, page 130 to page 135. It entails, after the mucoperiosteum has been lifted, removing as much bone substance from the vicinity of the root apex to be resected as is necessary for performing the operation. The resulting bone cavity has a characteristic spatial shape corresponding to the root apex. After about 20% of the total length of the root has been resected, in most cases a retrograde root canal cavity is produced, and this must be filled just like the root canal itself. In this case, it is possible to insert a pin into the root canal so that only a little filling material is used.
Intraoperative root fillings require that the root canal be irrigated with highly reactive reagents such as 3% strength H.sub.2 O.sub.2, 5% strength NaOCl, alcohol, etc. These irrigations emerge at the area of resection and are aspirated there, but it is not possible to avoid having a portion of the irrigations enter the bone cavity. In the case of retrograde filling, which is sometimes needed, it is also necessary to prepare the root cavity with highly reactive reagents, for example 40% strength citric acid. In this case as well, it is often unavoidable that liquid enters the bone cavity. On the other hand, the fillings have to be introduced into a dry root cavity or a completely dry root canal, and must be able to harden for a considerable time without liquid entering. Since the fillings must be introduced in excess, it is also often unavoidable that, because of the consistency of these fillings, a portion thereof enters the bone cavity and must be laboriously removed therefrom.
Oozing blood emerges from the surface adjoining the bone cavity and prevents drying both of the root cavity and of the root canal before introduction of the fillings, and contaminates the filling materials in their hardening phase.
For it to be possible, nevertheless, to carry out a satisfactory apicoectomy, it is necessary either to pack the root cavity tightly with gauze, to administer reagents which stop the bleeding due to a vasoconstrictor or astringent action, or to line the bone cavity with bone wax. In this case, it is not advantageous to administer epinephrine or the like, because of the long exposure time, the uncertain onset of its action, the uncertain duration of its action, and its hazardous side effects, especially since renewed bleeding may occur at each irrigation of the bone cavity between times. Although covering the bone surface with the aid of bone wax, which must be carried out with the bone cavity as dry as possible (after administration of hemostatic reagents), prevents further emergence of blood, it has the disadvantage that the wax particles must be removed again after the operation, which requires troublesome manipulation.
In order to eliminate these deficiencies, it has already been disclosed by Wilstermann, "Der retrograde Wurzelkanalverschlu.beta. mit Goldent", Deutsche Zahnarztliche Zeitschrift 29 (1974), pages 759 to 760, to place over the exposed root cross-section the ring-shaped loop of a ring-shaped instrument provided with a handle, which loop separates the area of resection from the surrounding retrogradely prepared bone cavity to such an extent that the root cavity and the root canal remain dry. In this case, however, a viewing restriction for the surgeon is unavoidable, and access to the area of resection is also restricted. In addition, this ring-shaped instrument has to be held throughout the treatment time. Obviously, however, this considerably impedes the work for the surgeon.
An object of the invention is therefore to provide an appliance of the type mentioned above, which remains in situ throughout the operation without having to be held, which allows clear viewing and free access to the resected area of the root apex and to the root cavity or the root canal, which can be produced easily and at low cost, and which can be introduced into the bone cavity and can be adapted in a simple manner to the particular spatial shape thereof.